Effects Of Soil Conditioner On Cd-Pb Polluted Soils And The Chemical Composition Of Tobacco Leaves

In order to improve the quality and safety of tobacco leaf,and to repair heavy metal contaminated soil,with flue-cured tobacco K326 as test material.The effects of application rates of the soil conditioner on main chemical components of tobacco leaves,soil physical and chemical properties,and microbia functional diversity were explored through a plot experiment in 2015.And another research on effects of soil conditioner on Cd-Pb form transformation in contaminated soil,contents of Cd and Pb in roots,stems,leaves and seeds of tobacco,which was conducted in 2016.The results of the study are as follows:(1)Adding different dosage of soil conditioner had a significant effect on main chemical components of tobacco leaves,and increased the total sugar and reducing sugar content of flue-cured tobacco,reduced the total nitrogen content,starch,chlorine and nicotine.T2 was most beneficial to improve the chemical composition of upper leaves,that is to improve the quality of upper leaves.(2)The soil conditioner significantly changed soil physical and chemical properties and there were significant increases in soil pH,organic matter,available phosphorus,available potassium.which increased by 2.2-8.8%?1.3-4.4%?1.8-8.8%?23.6-76.0% respectively.While alkaline nitrogen was no significant difference.It was found that the AWCD values was much higher when the soil conditioner was at proper weight percent.However,the AWCD values declined when too much the soil conditioner was doped,the soil microbial communities followed the order:T2>T1>T3>CK;The activities of species richness and McIntosh index were increased most significantly at the application rate of 0.2%,the enzyme activities were increased by 55.1%?88.4%respectively.Principal component analysis showed that the diversities and the carbon utilization ability of soil microbial community had a lot of discrepancies using soil conditioner.All in all,the soil conditioner can significantly increase soil nutrient content,which improves the soil microbial functional diversity,and that the appropriate application rate is 0.2%.(3)The soil conditioner changed the morphology distribution of soil Cd and Pb,facilitated the transformation of Cd and Pb from active high acid soluble state to the low active residue state,so that reduced the biological effectiveness and migrate ability of Cd and Pb.Soil pH,available phosphorus,alkaline nitrogen were positively correlated with acid-soluble Cd and Pb,but negatively correlated with the residual Cd and Pb.So it could promote the transformation of acid-soluble to residual,which could reduce the biological activity of heavy metals in soil by increasing soil pH,available phosphorus,alkaline nitrogen.(4)The soil conditioner was able to significantly affect contents of Cd and Pb in tobacco.Different parts of tobacco was different on accumulating heavy metals,The Pb content in roots was the first,and the Pb content in tobacco leaves was second,and the content of Cd in tobacco leaves was the highest.The application of soil conditioner significantly inhibited the absorption of Cd and Pb in tobacco leaves by contents of 70%.The recommended dosage of soil conditioner was 0.2%.